Small angle neutron scattering
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Students: Andisiwe Stuurman, University of Fort Hare Kwindla Nobaza, University of Johannesburg Merriam Ngulube, University of Limpopo Project Coordinator: Dr. A.I Kuklin JINR Summer student practice, 3-23 September 2011, Dubna
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Small angle neutron scattering. Students: Andisiwe Stuurman, University of Fort Hare Kwindla Nobaza, University of Johannesburg Merriam Ngulube, University of Limpopo Project Coordinator: Dr. A.I Kuklin JINR Summer student practice, 3-23 September 2011, Dubna. SANS Introduction. - PowerPoint PPT Presentation
Transcript of Small angle neutron scattering
Students:Andisiwe Stuurman, University of Fort HareKwindla Nobaza, University of Johannesburg Merriam Ngulube, University of Limpopo
Project Coordinator: Dr. A.I Kuklin
JINR Summer student practice, 3-23 September 2011, Dubna
Small Angle Neutron Scattering is a method used to investigate the properties of different materials by scattered neutrons at small angles.
Nuclear fission reaction – one incident neutron hits the target and emits an average of 2.5 neutrons, energy release ~ 180 MeV.
Spallation reaction is one where extremely high energy particles (e.g. protons) hit the target made of a neutron-rich material, “breaking” a heavy nucleus into highly excited fragments
1. Two reflectors2. Zone of reactor with moderator3. Chopper4. First collimator5. Vacuum tube6. Second collimator7. Thermostat8. Samples table9. Goniometer10-11. Vn-standard12. Ring-wire detector13. Position-sensitive detector "Volga”14. Direct beam detector.
In a SANS experiment, the wavelength of the incident beam and the scattering angle define , through the relation expressing momentum conservation in an elastic interaction:
- Q is the wave vector- λ is the neutron wavelength- θ is the scattering angle between the direction of the transmitted and scattered beams
2/sin4Q
The dimension of a probe is D = 2π/Q The range of Q (scattering vector) is
0.001--1 Å-1
Chemistry:- polymers- precipitates- surfactants- colloids- gels
Biology:- proteins- viruses- lipid aggregates- emulsificatorsMaterials
science:- alloys- glasses- composites- porous systems- grained materials - ceramics- powders
The following types of samples can be analysed using SANS, with applications across various disciplines.
ADVANTAGES DISADVANTAGES
The advantages that SANS presents, due to the neutrons’ properties are:◦ Contrast variation
method◦ Interaction with nuclei◦ Deep penetration
SANS is expensive. Neutron flux is very
low as compared to X-ray flux.
Interaction of neutrons with matter is weak.
Cannot be operated at small scale.
Verifying the spherical shell-like structure of apoferritin with SANS method of investigation
Determine the parameters of the structure: Radius of gyration Inner and outer radii
Use of different programs (Fitter 2.1.5, Primus, Origin 8.5) in order to compare the results
63.51
72.160.563
72.10672
th
g
g
R
R
Rtg
tg
From the experimental data gathered from the YuMO SANS Instrument we obtained the experimental curves;
Using Primus and Origin we determined the radius of gyration of apoferritin and compared them, obtaining similar results;
Successfully modeled the experimental plot with Fitter, thus obtaining the inner and outer radii for our sample;
Apoferritin has a spherical shell-like structure
L.A. Feigin, D I. Svergun, Structure Analysis by X-Ray and Neutron Scattering
J.Teixiera., Introduction to SANS applied to colloidal science.
Alexander Ioffe, Neutron Sources., Vol 15.,University Munster
http://www.engr.sjsu.edu/rkwok/phys275/.ppt http://www.ncnr.nist.gov/programs/sans/ http://www.jinr.ru
DST and NRF We would like to thank Dr A.I Kuklin and his
team from Frank Laboratory of Neutron Physics.
Also we would like to extend our gratitude to the organizers of the Summer Student Practice.(JINR, Dr Jacobs, Prof. Lekala)
